PSI - Issue 64

Nicola Nisticò et al. / Procedia Structural Integrity 64 (2024) 2230–2237 Author name / Structural Integrity Procedia 00 (2019) 000–000

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techniques are essential for determining material properties and creating structural mechanical models to evaluate an object's performance against seismic events, aging, and chemical exposure. 3. Data acquisition and elaboration The proposed CLOUD constitutes a complex system comprising multiple Digital Twins, necessitating the establishment of a clear ontology to conceptualize its domain. Depending on the specific domain, various ontology models can be adopted. For industrial production, Barth et al. (2020) proposed an ontology that encompasses data resources, external and internal value creation processes. Data resources encompass: a) data sources, b) data format, and data category. Data sources may originate from systems internal or external to the enterprise, or from the Internet of Things, such as a Smart City Platform (SCP). Data format denotes how the data is stored, categorized as either unstructured (e.g., photography, video, and recordings) or semi-structured. Unlike structured data, semi-structured data cannot be directly analyzed and processed. Data categories comprise information on state and process performance. In the context of Cultural Heritage (CH) and Historical Built Heritage (HBH), the utilization of ontology-based semantic conceptualization has been recognized as crucial (Colucci et al., 2021). This approach provides a standardized language for effectively representing these domains. An example of this methodology has been applied to the Castellina fortress in Norcia, Italy. Developing the ontology presents a significant challenge due to the diverse range of data sources, technologies, and techniques involved in comprehensively describing the Cultural Heritage (CH) system. These sources include data from various tests (both destructive and non-destructive), remote sensing data, geometrical and mechanical data, historical documentation, and analysis results. Integrating all these data types into a dynamic cloud environment is essential. In terms of 3D digitization techniques, Pavlidis et al. (2007) make a distinction between historical monuments and historical objects. Several technologies (Janga et al., 2023) can be employed for this purpose based on remote sensing that, without any direct contact, acquire data thanks to either active or passive sensors hosted in different vectors such as Unmanned Aerial Vehicles (Nooralishahi et al, 2021), Unmanned Ground Vehicles, aircraft, and satellites. These technologies include sensors that can span the wavelengths of the electromagnetic spectrum; as far as cultural heritage is concerned the following systems can be mentioned: optical, thermal, radar and Synthetic Aperture Radar (SAR), Detection And Ranging (LiDAR) that is based on laser technology; Multispectral and Hyperspectral. The need of the integration of different sensors (Fang et al., 2022) is becoming an important issue. Dynamic sensors, such as accelerometers, play a crucial role in recording the history of accelerations at specific points: a critical review is reported in (Abdulkarem et al., 2020) were the importance of wireless system is emphasized. Regarding cultural heritage objects and monuments in (Pau and Vestroni, 2008, 2013; Nisticò et al,. 2016; Costanzo et al, 2022) the authors studied important historical cultural heritages located in Rome (Italy) that are 1) the Colosseum (Pau and Vestroni, 2008) and the Basilica of Maxentius (Pau and Vestroni, 2013): recording of ambient vibration helped to evaluate the respect of standard levels; 2) the bell tower of Santa Maria in Aracoeli Church (Nisticò et al, 2016): several field tests have been conducted using accelerometers to acquire ambient accelerations as well as accelerations induced by bells under different dynamic loading scenarios; 3) the Villa Farnesina (Costanzo et al, 2022): geophysical monitoring and terrestrial laser scanner were adopted respectively for crack detection and evaluation of the level of vibration induced by traffic. It is worth noting, as observed by Inglese and Paris (2020), that although surveying activities should always be understood as a unified scientific process of knowledge acquisition, from a methodological standpoint, several phases can be distinguished (acquisition, processing, and interpretation). Each phase has its own specific issues that must be guided by dedicated protocols, which should not be seen as simplifying rules but as frameworks designed to support the definition of critical pathways. From this perspective, the applications performed on ancient Roman bridges within the framework of Inglese and Paris studies can serve as an interesting starting point for addressing the digitalization of cultural heritage with a holistic approach. For objects and paintings, specific techniques and technologies are employed. The definition of shape for sculptures can be achieved through techniques such as capturing video images or projecting light patterns onto the surface. Local texture information, as suggested by Forsyth (2002), has the potential to enhance the definition of surface features.